Smart buildings are in vogue. In the last years, it has become a common requirement to build self-contained buildings. These buildings may be able to satisfy most of their own needs—in particular energy needs—by generating resources internally. This may be achieved by reusing energy from waste water, use of solar energy, garbage recycling to smart heating, and so on.
In modern cities, there exist a lot of tall buildings—like office buildings, hotels, shopping centers, administrative state-owned buildings—with several elevators, which may be used continuously and which may require continual electrical energy. Traditional elevators may just fulfill its purpose in moving up and down between floors and consuming electricity, but may not offer other advantages like helping to reduce energy consumption in a smart way.